package/apparmor: fix compatibility with busybox grep

package/apparmor: fix compatibility with busybox grep

The following regex string in rc.apparmor.functions
"^/.*[ \t]+flags[ \t]*=[ \t]*\([ \t]*complain[ \t]*\)[ \t]+{" is broken due to
the unescaped { at the end of the regex pattern.
GNU grep ignors the error. However, the Busybox grep does not and throws the
error "unescaped character {"

Escape the "{" character to fix this issue.

Note: Upstream has rewritten large sections of the rc.apparmor.functions file
and the function this patch fixes will no longer be necessary after the next
version is released. However, it is not possible to easily backport the
upstream patches as the rewrite comes with new features that would not be
possible with a simple patch such as this one.

Signed-off-by: Adam Duskett <Aduskett@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>